Bake oven



F. A. HOPPE Dec. 13, 1932.

BAKE OVEN Filed May '7, 1952 4 Sheets-Sheet 1 i N ww. @Wm NIT TM. mw.um. h

1,890,681 PE F. A. HOP

OVEN 2 BAKE '7 1932 4 Sheets-Sheet Filed May F. A. HoPPE Dec. 13, 1932.

BAKE OVEN Filed May v, 1952 4 sheets-sheet s Dec. 13, 1932. F, A HQPPE1,890,681

BAKE OVEN Filed May 7, 1932 4 sheets-sheet 4 j J5 559 g J5 y PatentedDec. 13, 1932 AUNITED STATES PMPENTI OFFICE FRIEDRICH A. HOPPE, FCHICAGO, ILLINOIS, ASSIGNOB T0 SCHMIDT'SELUBITIES COM- PANY, 0F CHICAGO,`ILLINOIS,

a CORPORATION or ILLINQIS BAKE OVEN Application led lay 7,

This invention relates to bake ovens, and particularly to ovens in whichthe breadstuffs are carried through a circuitous path in which they arebaked. y

In such ovens the'breadstus are normally conveyed by trays which formpart of a conveyor, which\conveyor runs backwards and forwards throughsubstantially horizontal superposed runs interconnected at their ends,to provide circuitous baking chambers.

My invention is particularly concerned with an'oven of the directheating type, that is an oven in which the heating gases are admitteddirectly into lthe passages in which the breadstuffs are located, but itpossesses this type is a matter of considerable 'diiliculty and it isthe general object of this invention to improve this distribution. Thus,for example there is normally a tendency for one side of the oven toheat more strongly than the other and it has been practically unpossibleto completely remedy the defect in ovens which have been constructedheretofore.'

One of the objects of theinvention is to improve the manner in which thehot gases are supplied to the various chambers within the oven.

A further object ofthe invention is to imprcve the manner in which therecirculated gases are withdrawn from the various chambers 'of the oven.l

.45 A )further vobject of the invention is to proissz. senin 11.809,800,

vide means whereby the withdrawal from botll slides of the oven may berelatively contro e e A further object of the invention is to provide animproved interrelated control for the heating means and for therecirculation `of gases so that substahtially uniform conditions may bemaintained in the oven irrespective of variation of load, that isvariation of the rate of ysu ply of breadstufs tothe oven.

A fiirther object of the in'ventionis to pro-. vide an improved meansfor regulating the steam zone of the oven, whereby economy of ste'apland more uniform results are obtained.

A further object of the Vinvention is toprovide improved means wherebythe removed products of combustion may be exhausted at Ialcontrolledrate and at an advantageous position.

ther objects, advantages and capabilities of the invention will appearfrom the following description pf a preferred embodiment thereof takenin conjunction with the accompa ing drawings, in which igure 1 is alongitudinal section through 70 an oven embodying my invention;

Fig. 2 is a 'transverse sectional view thereof ta en on the line 2-2 ofFig. 1;

Fi 3 is a transverse sectional view therel of ta en on the lin'e 3-3 ofFig. 1;

Fig. 4 is a plan v iew of the oven;

Fig. 5 is a fragmentary sectional detail view taken on the line 5-5 ofFig. 1, and

Fig. 6 is a fragmentary side elevation, partly in section, showing amodified construction of recirculation control.

Referring to the drawings, the oven, which l is substantiallyrectangular in shape, comprises internal partitions which definehorizontal runs 10, 11, 12 and 13 through which 85 extends a continuousconveyor shown by wa of example as a plurality of trays 14 whic dependfroml trunnions 15 which are connected by chains 16 in series,which-chainsl ride upon guides in the upper part of eachwhich is thehighest run, they run and pass over sprocket wheels or the` like 18 soas to mpve from one run to another. After the trays 14 pass inwardlythrough the run 10, outwardly through the ru'n 11 and inwardly throughthe run 12, descend through a vertical run or flight 19 and passoutwardly through the lower run 13 to the unloading and loading position20, at the front of the oven.

The oven may be heated by any suitable fuel, for example gas, which issupplied through a pipe 21 and delivered to burners 22 through two pipes23 and 24. The pipe 24 is provided with a valve 25 whereby the supply ofgas may be manually controlled. The pipe 23 is provided with a valve 26the actuation or control of which will be hereinafter descrf bed. Theburners 22 deliver their products of combustion into an enlarged chamber27 into which extends a downcomer 28 which returns the'gases to berecirculated. The mixture of recirculating gases andhightemperaturecombustion gases passes from the chamber 27 through anoutlet 29 and is delivered to a fan or blower 30 which `discharges thestream into a main supply duct 31. The main supply duct 31 is located inthe bottom of the oven and extends there- Ithrough for a substantialpart of its length.

The runsV 10 and 13 are heated indirectly, that is they are heatedthrough impervious partitions 32 and 33. Means are provided forcirculating heated gases through the charnbers 34 and 35 provided on theunderside of these partitions. The runs 11 and 12 are directly heated,that is the hot gases are de-v livered directlv into the chambers orspaces provided by these runs. The hot gases are discharged into thechambers 34 and 35 and the runs 11 and 12 from bxes'36 which extendtransversely of the oven and are provided in their` upper face Withdischargeslits which extend thewhole length of the boxes. The gasesareexhausted by means of boxes 37 which also extend transversely of theoven and are provided with longitudinal slots, preferably along oneside. Thus it will be seen that the incoming gases are projectedupwardly while the gases removed are col- ,lected from a point near theHoor of the run or heating chamber, as the case mav be. Thus the heatedgases, in the case of the runs 11 and 12 are projected verticallyagainst the undersides of the pans 14 and between the pans up to theupper walls of the runs. After the gases have lgiven up a portion oftheir heat and have dropped to the floor of the runs they are removed bythe boxes 37. The

i and 35 is similar.

The hot gas supply boxesy 36 receive their hot gases from the mainlsupply duct 31 the other boxes receive their gases from the N otherside This feature results in a much more uniform heating of the trays 14and a much more satisfactory operation of the oven.

The exhaust boxes 37 communicate at one end with conduits 39, which arealso located in the side walls and arranged alternately so that thealternate boxes 37 along one run discharge into conduits 39 in one walland the other exhaust boxes 37 discharge into conduits 39 inthe otherwall. This feature like- Y wise materially improves the uniform heatingof the oven. The conduits 39 are connected by horizontal conduits 40,which are located inthe top of the oven, with main exhaust duct 41,which is located on top of the oven and extends substantially centrallythereof. I prefer to provide a longitudinal partition 42 down the centerof the main ex-` haust duct 41 so as to separate the gases dischargedthereinto by the conduits 40. I, provide at the end of the partition 42means controlling the exhaust flow through each side of the oven. Thismeans may suitably take the form of adainper 43 which can be located inany desired position so as to equalize the heating on one side of theoven with that on the other.v

, The main exhaustduct 41 gives into a conduit 44 which enters at rightangles into the pipe 28. Adjacent thev pipe 28 the conduit 44 isprovided with ayhorizontal partition 45, the outer end of which carriesa damper 46 which is adapted to close the pipe 28, in, continuation withthe partitionv 45. At the inner end of the partition 45 I provide adamper 47 which is provided with a horizontal axis about which it may beturned so as to divert a desired portion of the 'stream 'f gases passingthrough the conduit 44 above the partition 45. These gases possessconsiderable speed owing to the circulation setk up by the blower 30,andtheir momentum is suflicient to carry them out to the atmosphere throughthe upper part ofpipe 28,

notwithstanding the suction or low pressure created in the conduit 44 bythe blower 30. This action isI assisted by the high temperature of thegases, the upper portion ofthe pipe 28 serving as a stack. The remainderofthe gases, which preferably comprise about ninety percent of thetotalexhaust' lgases,

passes downwardly through the pipe 28 into the chamber A27 in the mannerdescribed above.

The damper 46 is preferably vemployed when oil is used asl fuel. It isopened When the through vertical conduits 38 located in the *il burneris started so .as to vent the soot side walls of the oven. *Asl will benoted, more and other products of incomplete combus- 13 .6,5 thisinstrument being capable of\`being lset 'objection to a considerabledegree by locating within the run 1.0 and at a lowlevel therein asuitable number of boxes 49, which extend across the run 10 and areprovided intheirA upper faces with slots 50.

The boxes 49 are connected at one end by a suitable duct 51, suitablyloated -in o'ne side wall. The duct 51 communicates with a duct 52, alsolocated in said side wall, which duct feeds into a. duct 53 located atthe top of to any desired temperature by means of a handle 65. Theinstrument 64 is energized by leads 66. When this desired temperature isattained crcuits are completed through leads 67 which throw switcheswithin a relay 68 so as to divert'power from lead 69 to suitable motors70, 71- and 72 through a pair of conductors 73. When the temperaturefalls a certain amount, for example three degrees, the reverse actiontakes place and the switches of the relay 68 are thrown in the oppositedirection so as to send the current through another pair of theconductors 73. The motors 70, 71 and 72 are of known type, beingreversible motors equipped w'th limit switches so that at the end of thepredetermihed operation in either direction they stop, making thecircuit for the other pair of con.- ductors 73 to operate them in theopposite direction, when said conductors are energized in response tochange of temperature. u It will b e understood that the instruments 64,68, 70', 71 and 72 are of known type and are the oven. Means adapted toproduce sucti0n^ not claimed broadly, the present invention areassociated with the conduit 53 so as to withdraw relatively cold gasfrom a lower level of the run 10.,.thereby avoiding" the expulsion ofthe steam laden gases through the `feed opening. Above the feed opening20 `is provided a' hood 54 which extends upwardly' into a duct 55. AThehood 54 preferably contains a transverse partition 5,6l which terminatesat the lower end of the duct 55 and is provided there -with a damper 57which may be adjusted so as to regulate the withdrawal of 'the hot gasesdischarged through the opening 20, away from the operator whois normallystationed at the feed opening. The duct 55 is providedwith an exhaustblower 58, drivenin any suitable manner, and its upper end is reduced`slightly as shown at 59; The upper endof the duct 55 extends through achamber' 60into which 45. communicates the' duct 53. 'A gate 'valve orthe like 61 controls-the supply of exhaust gases from the codut 53 tothe chamber 60.

Yco

The upper' end of the chamberGOtapers intopropinquity with thetapered-end 59 of' the duct and extends upwardly therebeyond in the formof a stack 62.L The tapered portion of the chamber '60 and the taperedend 59 of the duct 55 'cooperate to provide a Venturi e'iect so that theflowof gases through the duct 55 creates a suction within the lchamber60,v which suction effects the removal of ,gases fromthe lower levelofthe run 10, through the boxes 49? In accordance with my invention Iprovideautomatic mechanism whereby 'both the recirculation and the`supply of highly heated' gases are correlated and adjusted. At 63I showdiagrammatically a thermo-electric device, such asa'thermo-couplewhichis connected toan instrument 64 ofknown type,

Jthe blower 30.

being concerned onlyv with their application to a bake oven. The motor70 is connected by suitable linkage 74 with the valve 26 vso that thisvalve is completely closed in one extreme position of the motor and isfully open .in the other extremev positon. The

motor 71 is connected through asuitable linkage 75 with a damper 76located in the downcpmer 28.

. The motor 72 is connected through a 'suitable linkage 77 with a damper78 located 'atthe outlet of the blower 30. The damper 78, is adapted tolimit `the low of gasesand ynot completely stop same. For example, itmay be adapted to permit half the normal flow of gases to take placewhen in its closed tion. lThedamper 76 is adapted to partially closedowncomer\28 so as to increase some-,

osi-

what the suction in chamber 27, with the result that suiicient airisdrawn in to supply the burners notwithstanding the restriction providedby ther damper` 7 8 in the outlet of- It will be undestood that when'themotor '70 is actuated to Aclose the valve 26, the motors 71 and 72 aresimultaneously actuatedthe recirculating gases in the chamber 27.

Supposing the temperaturincreased unduly. for example owingto fadecrease -in the amount of breadstuffs supplied in the feed opening 20,the temperature reachingthat valve 26 to be open, the

predeterminediby the instrument 64. Then circuits are made through apair of conduc tors 73 so as to actuate the motors 7 0, 71 and 7 2, withthe result that the fuel suppliedI is cut down and the amount of gasesrecirculated is likewise cut down. The devices are preferably adjustedso that the ratio of gases recirculated to hot gases supplied ismainel() Su tained substantially the same in both cases. In thiswaysubstantially uniformity of temperature is maintained throughout everypart of the oven irrespective of whether the hal fire.

ln the modified construction shown in Fig.. 6, a by-pass 79 connects theoutlet of the blower 30 with the exhaust vconduit 44. The

damper 78 is replaced by a damper 80 Which is adaptedl toclose eitherthe by-pass 7 9 or the entrance to the main supply duct 31. Thedamper`80 is controlled by the motor 72. ln

V this modification the motors 71 and 72 are 29 actuated simultaneouslyso as to close `the valve 26, move the` damper 7 6 to closed po-` sitionand move the damper 80 so as to close the inlet to the main supply duct31. Thus (it will be seen that the fuel supply is reduced to aminimumand the supply of gases to the oven is shut ofi', the blower 3() servingto circulate gases throughAby-pass 79, eX-

haust conduit 44, downcomer 28 and cham-` ber 27. The closing or partialclosing of `the damper 76 increases the suction within the chamber 27 sothat an adequatev supply of air is drawn in, to supply the burners.During this operation, which continues until the temperature of the ovenfalls to the de- Having thus described my invention, what I claim as newand desire to secure by Letters Patent of the United States is:

l. A bake oven comprising a plurality of superposed zones, horizontalpartitions separatingsajd zones, said zones communicating at theirendsin series to form a continuous chamber, means for injecting steam intothe initlal baking zone, and means for withdrawing gases at the level ofthe lower partition of ff said zone.

back flow of gases through said run .and feed opening.

3. A bake oven comprising a plurality of .superposed runs connected attheir ends in ly of gas or other fuel is at full lire oriA series toform a continuous chamber, horizontal partitions between 'saidruns,kmean s for injecting steam into the initial baking run,conduits/communicating with the initlal baking run at the bottompartition thereof, and mechanical means for creating suction in saidconduits.

4. A bake oven comprising a. plurality of substantially horizontal vrunsconnected at theirvends to provide a circuitous baking chamber, saidoven being provided with a feed opening, pipes for injecting steam intothe initial baking run, conduits opening into said run at a low levelthereof, and a blower adapted to remove gases discharged through saidfeed opening and adapted to create suction within said conduits.

5. A bake oven comprising a plurality of exhaust pipe, and Venturi meanswhereby the j 2. A bake oven comprising a pluralityof f substantiallyhorizontal runs connected at n their mends to provide a circuitousbaking chamber. horizontal partitions between said runs, said 'ovenbeing providedv withfa feed opening, pipes forinjecting-.steamfinto'thev i 'initial baking run,l conduits opening intosaid run between the trays therein and the hori`` `zontal partitiontherebeneath` and means for .relation connected at their en s to formn aexhaust flow creates a suction in said conduits..

6. A bake oven comprising a plurality of substantially horizbntal runsin superposed relation connected at their ends to form a circuitousbaking chamber, a main for supplying hot gases. a main for'exhaustingcooler gases, a plurality of supply conduits 1n each run open across theoven, andvertical conduits in the side walls communicating bei tween thesupply main and supply conduits,

run openy across the o ven, and vertical con saidvertical.conduits/beingstaggered one on rection thereof.

8. A bake ovenrcomprising a. plurality of y substantially horizontalruns 1n superposed circuitousbakingchamberya main for supleach sideofthe oven in the longitudinal diplying hot gasesa main `for exhaustingcooler gases, afplurality of supply conduits in each run open across theoven, vertical conduits in f abstracting gases therethrough to reducethe the side Iwalls communicating between the gases from the runs, aplurality of vertic vrelation conne lets from the conduits on one sisupply main and supply conduits, said yertical conduits being staggeredone on each side of the oven in the longitudinal direction thereof, apluralityof exhaust conduits in each run open across the oven, andvertical conduits in the side walls communicating between the exhaustmain and exhaust conduits, said vertical conduits being staggered one oneach side of the oyen in the longitudin direction thereof.

A bake oven comprising a plurality of substantially horizontal runs insuperposed cted at their endsto form a circuitous baking chamber, meansfor supplying hot gases, a main for exhausting cooler gases from theruns, a plurality of vertical conduits communicating with the exhaustmain and adapted to supply exhaust gases thereto, said Vertical conduitsbeing located on both sides of the. oven, and a partition within saidexhaust main separating the inde from those on the other side. i

l10. A bake oven comprising a plurality of substantially horizontal runsin superposed relation connected at their ends to form a circuitousbaking chamber, means for supplying hot gases, a 4main for exhaustingcooler gases from the runs, a plurality of vertical con)- duitscommunicating with the exhaust main and adaptedto supply exhaust gasesthereto, said vertical conduits being located on both sides of the oven,a partition within said exs haust main. separating the inlets from theconduits on`\ one side from those on lthe other side, and means at theend of said partition operable to'equalize the iiow on each sidethereof. A Q

11. A' bake oven comprising a plurality of substantiallyhorizontal runsin superposed relation connected at theiriends to form a circuitousbaking chamber, means for supplying hot gases, a main for exhaustingcooleil` a conduits communicating with the exhaust main and adapted tosupply exhaust gases thereto, said vertical conduits being located onbothsides of the oven, a partition within said exhaust main separatingthe inletsfrom the conduits on yone sideyfrom those on the other side,and a damper pivotally mounted heated outlet blower gases c gases to therecirculating gases, an. for gases on the suctionv side of the locatedso that the momentum of the arries them out of the system, and a damperada ted to control thev flow of gases through said) outlet.

14. A. bake oven comprising la baking chamber gases through the oven inheating relation to the breadstu-ffs, means- `for supplying highlyheated gases to the recirculating gases, an outlet forgases on thesuction side of the blower located so that the momentum of the gasescarries them out of the system, and an adjustable damper pivotallymounted adjacent said outlet and presented against the stream.

15. A bake oven comprising a. baking chamber, a blower adapted tocirculate hot gases through the oven into direct contact with thebreadstufs, means for supplying highly heated gases to the recirculatinggases, an outlet for gases on the suction side of said blower so locatedthat the momentum of the gases carries them out of the system,- and astack into which said outlet leads.

16. A bake oven comprising a baking chamber, a blower adapted tocirculate hot gases through the oyen into direct contact with thebreadstuffs, means for supplying blower adapted to circulate hot lhighly heated gases to the recirculating ros circulation .of gases,means for` supplying highly heated gases to the recirculating gases,meahs for controlling the said heat supply `means, and means 1n saidconduit on each side of said; heat supply means for controlling the flowof gases through theN conduit, and means responsive to oventemperaturefor actuating said controlling '115 18. In a recirculating bake oyen, incombimeans in unison.

at the'end 0f the partition adapted@ equalze'nation, a conduit forremoving exhaust gases gases carries them out of the system.

13. A bake o ven comprising a baking chamber, a blower adapted tocirculate hot gases through theoven in heating relation to '55 thebreadstuffs, means for supplying highly 1 9. In a recirculating bake er,a blower bination, a conduit for removing exhaust gases from said oven,means for removing a portion thereof from the system, a mixing chamberinto which said conduit dischar es, a fluid fuel burnerfor supplyinghigly heatedgases into' such chamber, a blower adapted to withdraw mixedgases from said chamber, a conduit adapted to receive said gases andsupply same to the oven, 'a by-pass connecting' last said conduit tofirst saidconduit, a damper in the first said conduit between saidby'pass and said mixing chamber,

a'damper in last said conduit adapted to close said conduit and to closesaid by-pass, a valve controlling said fuel supply, and temperatureactuated electrical means for controlling'said dampers and Valve incorelation. .y i

20. A bake oven comprising a baking chamber, a conduit connecting onepoint of the chamber .to another point thereof, a blower in said conduitadapted to pass gases A therethrough, and an exhaust conduit having an'open mouth in the first said conduit on the suction side of the blowerand. directed against the How of the stream whereby the momentum ofthegases tends to exhaust a part thereof through said mouth.

In witness whereof, l hereunto subscribel my name this 28th day ofApril, 1932.

y aambeien A. Horen,

